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Below are two variations of the proposed design for a mechanical valve, which utilizes a inverse lever arm float and plunger to close off the flow of fuel. For now, no dimensions are finite; this is just to demonstrate and compare functionality. With the float arm distanced from the central axis, unwanted interaction with the torch wick is largely avoided. For ease of construction, we have elected to create a replica torch tank out of 3-D printed plastic, as the model torches we were given are sealed in such a fashion that the tank cannot be accessed without causing permanent damage to the torches we received. Example code for the capacitive sensing and Bluetooth networking can be found here.
Mechanical:"Bottom Sealing" Design "Side Sealing" Design Open 
This plunger design allows for the fluid to flow around the smaller diameter plunger head and out the holes in the sides and top. 
With this design, the plunger sits flush along the inner wall of the diffuser; as the float raises, the sides of the plunger head cover the holes, sealing the valve. Closed 
As the fuel level rises, it pushes the plunger down until it presses closed against the bottom of the diffuser head. A rubber gasket would be placed in the bottom for the plunger to press into to create a seal. 
As the fuel level rises, it pushes the plunger down, covering the holes in the side of the diffuser head. A downside of this design is that the direction of motion/force is perpendicular to the flow direction, so all sealant "force" must be created solely by a gasket. Electrical:
The image below captures all the pieces of the torch electronics. Examining the image from the top left to the bottom right we see: 3.3V regulator, 10uF and 0.1uF capacitors, the analog discovery module for use in debugging, 2.1mm barrel jack adapter, solar panel holder with panels inside, Nordic dongle soldered to the Pimoroni prototype board and held in the breadboard with common headers, the solar charger, and the 1200mAh LiPO battery. Missing from this is the copper tape which will be added at a later date as it was order much after the parts seen here.
Starting with the micro-controller and sensor technology the system is very simple hardware wise. With the dev kit attached to the prototype board all the pins are broken out and can be wired via jumpers. Power, ground, and the copper tape capacitive sensor would all we wired to in this way. The power would come from the solar panel setup but first it will pass through the regulator circuit formed by the two capacitors and 3.3V regulator IC. The solar panels would be wired in parallel to keep the voltage constant but increase the charging current. They would then pass thought the 2.1mm adapter into the charger board. The charger board would then charge the LiPO battery which would in turn power the electronics in the head. Once the copper tape sensor is built this is all that is needed to form a working prototype of the torch head electronics. The diagram and BOM does not include wires but it can be said that 20-24 AWG is sufficient in wiring all pieces of this system. Below is what the copper sensor would look like. As shown it is a piece of the copper tape attached to a cardboard dielectric that will function like a capacitive touch sensor when paired with the micro-controllers on-board oscillator. As for the software of the system, most of the code can be found in example projects from existing libraries in Nordic semiconductors website. With the system configured as previously stated the code would check the sensor every 10 or so minutes and send that data over Bluetooth mesh to the base station which would relay that information to the BugTorch app over WiFi.
Relevant Files